Method and apparatus for locating leaks in wells



lea-ann sa P Ipem XR 293239455 N .ugx 28, 1945. H, ABADlE 2,383,455

METHOD AND APPARATUS FQH LOCATING LEAKS IN WELLS I Filed NOV. 28. 1942 `2 Sheets-Sheet l iAug. 28, 1945.

H'. G; ABADIE METHOD AND APPARATUS FOR LOCATING LEA-KS IN WELLS I Filed Nov, 28. -194'2 2 Sheets-Sheet 2 All Y w J .wrm uw 55 lfenr UNITED; STATE Patented Aug. ze, 1945 s PATENT oFFics ,METHOD AND APPARATUS FOR LOCATIN I LEAKS IN WELLS I `Henry G. Abadie,v Kettleman North Dome Hills,

. Calif., assignor-of one-half to Frederick G. f

Bradbury, Los Angeles, Calif.

Application November 28, 1942, Serial No. 467,239

4c1aims. fernab-wa '7 2 'S-f My' invention relates `to``an improved method andnapparatus for locating leaks in wells. y More particularly the" invention provides, means by which leaks caused by cracks, holes or other passages at unknown depths 'can be Vlocated in the casing, tubing or other ducts employed in oil, gas or other-types of wells. 1

#An object therefore of this invention is to provide a precise and dependable method and simple and effective apparatus by which leaks in the casing, tubing or'other ducts of oil, gas or other types of wells can be quickly. and accurately determined at a minimum of expense and hazard. A particular advantage attained by my invention is a considerable saving in cost of vrepairing wells when leaks occur. Further objects and advantages willbe apparent from the following description and the drawings forming vpart thereof, in which'Fig. l'i's a, diagrammatic view of an oil well showing the manner in which my improved method is applied and an apparatus by which the improved method 'can be carried into practice for locating leaks-one of the leaks ,being indicated in a duct which is'usually termed the casing oil string; Fig'. 2 is an idealized diagrammatic View, illustrating the application of my improved method: and Fig. 3 is a diagram showing a thermal survey of an actual run made by the application of my improved method.

In mines and oil wells the increase oftemperature with depth is an established fact'. This substantially uniform increase of temperature is known as thev geothermal gradient. This gradient varies in different areas and it is known to Vary in different sections of the same eld. However, in any one area there is little variation in the rate of temperature `change from the surface to the maximum recorded the gradient will approximate a straight line but the fluids that enter the well will have a marked effect on..the temperature gradient opposite the point of entry of gas, oil and Water due to their different specinc heats, and'4 in the case of gas the cooling which results from expansion, the innuence of which is carried upward by the rising column Aof uid.

My approach to the problem of locating leaks in the various ducts employed in a well has been l to alter or change the above flowing or geotheratv the leak. Water can be employed as a cirdepth. In many ofthe thermal surveys it has of contact. rlfhereiore, the conductive nature of the sediments determines the manner in which the ytemperature gradient gradually resumes the normal geothermal gradient in any particular area under observation..- The temperature gradient when the well is. placed on production will be found to vary. Over limited distances mal gradient, depending whether the Well is flowing orI shut in. Essentially', the idea is to precondition'the well so as to induce or Vcause a decided temperature change at the point of the leak of such magnitude that it may be recorded, and to visually indicate such changes and their depth in the well. Temperature changes, which I term temperature ancmalies,'adjacent .to leaks in wells are effectively indicated by introducing extraneous gas, water, or oil into or between the strings of casing or tubing in the well to establish equilibrium temperatures. This'means that the uid'which is introduced into the well is caused tocirculate Yinthe well, that is return to the surface through another path and through the leak* Or, ifit cannot return to the surface, and itcan be forced away through the leak back into a porous formation the sameeffect may be obtained.` This increased anomaly producedbyV my invention is precise, decided and sufficient to enable'accurate recording for practical purposes asto variation in degree of temperature and depth of locationin the well.

In practice, gas has been found to be a good circulating medium to produce equilibrium temperatures and to induce a temperature anomaly culating medium but the introduction of water in an cil or. gas well-has been found objectionable as: it can damage the productive sands. Also oil can be employed but from experience it has been found diiiicult to circulate oil through an extremely small leak in the casing. Then too, in a large percentage of wells the formation pressure is so lowthat it cannot supporta co1- lumn of fluid in the well. However, gas is frequently more easily available and by the use of aY small'compressor it-is possible to quicklyv increase the pressure of gas to the desired point where it" can beforced into and circulated 'ihrc'ough the well for the purposes above speci- In Fig. 1 of the accompanying drawings, two stringsA of casing are shown; the outer casing A,

termed the water string, and the inner lcasing B, termed the oil string. A string of tubing C is shown within the oil string. These ducts are shown assembled and mounted in a suitable head fitting D above .the surface and incorporated into what is commonly known as the.

annulus of the well, which separates the ducts and provides an ingress duct I0, entering the space between the water string 'and lthe oil string, an egress duct II emerging from theV space between the oil string and the tubing, and a service duct I2 connected with theupper Aend-,-l j;

of tubing C and shown controlled by the hand operated shut off valve I3.Y rlhe service duct is shown provided with a now line I1, which is con-f tact to measure the travel of the line and gauge the depth of the recorder in the Well. The ther-` mal recorder may be of any usual type. One

trolled by a suitable shut o valve i 8 and pro-j vided with a pressure indicator IS, The water string A is cemented at I4 in the ground and mented at I5 above the top of the perforated lower end I8 which is juxtaposed to theoil and gas formation. These parts are all of usual type such as are employed in oil well practice.V

For a hypothetical illustration of my invention,

let it be assumed that there is a failure through a leak such as E, `of unknown depth in the well. The attendant is aware of some fact that leads one to believe thata leak exists in the water or oil string or tubing as the case may be and it is imperative to know the approximate source in orderto effect a repair. The well is rst shut in by closing the valve I8 in the ilow line Il. Gas pressure is applied at field line or compressor discharge temperature to the annulusof `the water and oil string at the surface of the ingress .i i

duct Ill. This gas pressure preconditions the Well and depresses the iiuid, if present, in the annulus, either forcing part of it back into some permeable sand or fractured shale or all of it through the leak E, into the inside of the oil string., Eventually the top of the fluid is depressed to the level of the leak and gas starts owin'g through the leak. After suiiicient gas has passed through the leak the column of fluid on the inside will be lightened to the point where the gas and iiuid will start to rise. Finally, a point isv reached where the gas and fluid reaches the surface. rI'he lightening of the iiuid column. on the inside may in` duce the well to flow.. If the well iiows it will aiect the temperature anomaly at the leak, how- .ever it doesnt obscure the results if suicient gas is circulated. The gas should becirculated for a sufficient period to establish equilibrium-temperatures in the ducts of the well and a decided temperature anomaly at the location of the leak. f y The period may range over several hours and preferably until a maximum volume of y.gas is being circulated through the leak. In practice this period has been from six to twenty-four hours. In general, there will be a large pressure drop across the leak in the casing and this results in a relatively large temperature drop which causes a cooling of the casing. at this point. In the illustrated case shown in Fig. 1, if the temperature change at the leak is sufficient there will be an absorption of heat from the tubing at and above the point of entry.

In the practice of my invention a suitable thermal recorder, such as F, attached to a. sounding or lead line such as 20, is placed in the upper end of the tubing C. This recorder is lowered through the tubing in the well after the latter has been preconditioned. A suitable lubricator 2| is attached to the outer end. of the valve I 3, with line YZI) passing therethrough. 'I'he'lubricator permits type of recorder which' may be employed is a self "'contained'unit which automatically and continu ously records temperature in synchronism with "fthe rate at which it is lowered into the wen, the

e -rateof feed being correlated with the temperathe lower end of the oil string B is shown ceture recorded. Another type is that which provides continuous recording of temperature, the

recordmade being visible at the surface ofthe well-While making a run. The lowering of the recorder is by any suitable means, such for illustration as the motivated reel 26, which is driven by a prime mover such as the internal combustion engine 21.. This reel is controlled to expend the line at regular speed, by any suitable reduction mechanism, not shown,. the time element being correlated with the record made by the recorder as above stated, whereby thedepth in the well at which the temperature is recorded can be determined during orafter the recording operation. Anyfluid-inside the 4tubing facilitates the transferA of heat to the recorder and at the same time minimizes lag in recording variations of temperature. It is to be understood that Fig. 1 of the drawings illustrates the apparatus above described only diagrammatically.

Atypical thermal survey illustrating the practiceof my invention is shown by Fig. 2 of the drawings and illustrates by the graphical record, ,when compared with the well illustrated in Fig. l, the location of. a leak. ItV will be-noted that the results are direct and very simple to interpret,

- which is-a distinct advantage. These direct results-are due to the precise and decided temperature anomaly produced by the controlled conditions in the well. In general thermal Work this is not usually` the case and often the survey is d icult to interpret, It will be observed that the recording of the temperature anomaly is correlated with the thermal gradient-of the fluid above and below and that variations in temperature of the anomaly itself disclose decided temperature. characteristics which may be employed as determining'factors for various uses in a well.

Wells usually employ several-strings of casing. By shutting in portions of the tubing or strings of casing in any well and circulating iiuid under sufficient pressure in the manner stated, my improved method and apparatus are applicable within the skill of the operator for locating the intrusion of water or other leaks. The determination of the depth of a'leak ina well has in the practice of my invention been' sufficiently close for all practical purposes. In tests made at varying rdepths I have found my improved methd and apparatusto be successful, inexpensive and to require a minimum of time in determining the location of leaks. l

My method and apparatus are also applicable forlocating more than one intrusion of water or other-leak .by a single run of a thermal recorder or indicator in a well as isl illustrated by the .survey 4diagram in Fig. 3,. which is subspirit of the invention to make this and other modifications in practice.

In accordance with the patent statutes, I'have described the principles of operation of my invention together with the apparatus and mode of operation which I now consider to representthe best embodiment thereof, but I desire to have it understood that the invention can be variously modified and applied to uses other than those above set forth, Within the spirit thereof and within the scope of the following claims.

I claim:

1. The method of locating a leak in a duct between outer and inner chambers within the bore of .a well, comprising, injecting a comparatively large volume of gas from a controlled outside source into one of said chambers under sufficient predominant pressure so as to overcome formation pressure of uid, establish equilibrium temperatures in said chambers, discharge through said leak and induce a temperature anomaly adjacent thereto, and measuring the temperature gradient of the well includingvthe temperature anomaly.

2. The method of locating a leak .at unknown depth in va duct between outer and inner chambers within the bore of a well, comprising, closing in the well and injecting into one of said chambers and through said leak in to the remaining chamber a suflicient volume of gas. from an extraneous source Iat sufficient predominant pressure so as to overcome formation pressure of fluid, induce equilibrium temperatures in said,

chambers and a temperature anomaly adjacent to said leak, and measuring the temperature gradient of the well including said induced temperature anomaly.

3. The method of locating a leak at unknown depth between outer and inner chambers within the bore of a well, comprising, closing one of said chambers, forcing gas into said closed chamber from an extraneous source and through said leak into the companion chamber in sullcient quantity and at sufficient predominant pressure to overcome formation fluid pressure and induce a decided temperature anomaly adjacent to said leak, and measuring the depth of said temperature anomaly in the well.

4. The method of locating the depth of a leak between outer .and inner substantially clo-sed chambers in the bore of a Well, comprising, circulating gas from the surface above the well under suilicient predominant pressure to overcome formation uid pressure through said leak until j a state of equilibrium is produced in said chambers and gas under sufficient pressure and in suicient quantity is released through said leak to produce a decided temperature change adjacent thereto, measuring the temperature at varying depth including that of the leak in the bore of the well, and lcorrelating the temperature measured in the well with depth to deduce the depth of said leak by said induced change. in

temperature,

. l HENRY G. ABADIE; 

